Although the concept of a fiber optic laser is not new, early devices were multimode and synthesized from batch melted glasses which did not have the nearintrinsic loss or high bandwidth of current optical fiber. It has only been within the pass few years that high performance, single mode, fiber lasers and amplifiers have been demonstrated using telecommunicationsgrade silica fiber. Recently, this work has been extended to other glass systems and a Nd.sup.3+ -doped fluorozirconate heavy metal fluoride (HMF) glass multimode fiber laser has been demonstrated at 1.05 micrometers as discussed by M. C. Brierley and P. W. France, "Neodymiumdoped fluoro-zirconate fiber laser," Electron, Lett. 23, 815 (1987). However, all these devices have operated at 0.9, 1.0-1.1, or 1.55 micrometers and the important goal of obtaining a laser/amplifier in the major telecommunications channel at 1.3 micrometers has remained elusive. Prior to the invention disclosed here, the glass fiber laser operating closest to this important transmission band emitted at 1.4 micrometers for Nd.sup.3+ -doped silica as discussed by H. Po, F. Hakimi, R. J. Mansfield, R. P. Tumminelli, B. C. McCollum, E. Snitzer in their article: "Neodymium fiber lasers at 0.905, 1.06 and 1.4 micrometers," Abstracts of Annual Meeting of Optical Society of America, paper FD4, P103 (1986). Other reports of Nd.sup.3+ -doped glass lasers in the 1.3-1.4 micrometers region have been for bulk lasers of borate glasses with operating wavelengths ranging from 1.35 to 1.40 micrometers.